Is it true that children should not be forcibly pulled away from games? But then how to limit the time at the computer?

Why do you have to force him away? Agree in advance how much time he can spend at the computer and let him control it himself. Nowadays there are really colorful and exciting games (for example here), it's hard to stop. You just need to help your child a little bit, but banning is not an option nowadays. 

Depends on the age, on the genre, even from what time the child is playing. Before going to bed it is strictly forbidden to allow the floor games, and in general it is worth to watch carefully how the child behaves after such a pastime. We had a period when the children became uncontrollable after playing on the computer and we had to limit it 

they should be encouraged to have different hobbies and not look so much at the screens, it's not good for our eyes and they could get addicted to it. I can relate to this because I always played on the computer or game boys when I was a kid and I regret most of that time could've been done with more productive things like learning actual stuff, places to go and do, etc.